Spatial and temporal diversity for debris-flow meteorological control in subarctic oceanic periglacial environments in Iceland

Slopes in fjord environments of Iceland are prone to debris-flow initiation, responding to a wide variety of meteorological triggering factors, such as rain on snow, rapid snowmelt, long-lasting rainfall or intense rainfall. If all fjord regions have similar debris flows with regards to their magnitude, their meteorological control is diverse both in space and in time. Debris flows in Northwest Iceland are triggered mostly by rain on snow and long-lasting rainfall, while snowmelt is more characteristic in North Iceland, and rainfall has a clear impact in East Iceland. Most debris-flow events occur on a single slope, and only a few are recorded at the same time in different regions. Observations of the threshold values underline the diversity of debris-flow initiation, occurring with huge amounts of sudden water supply as well as with very moderate ones. Copyright (c) 2007 John Wiley & Sons, Ltd.